Recurrent calcific periarthritis, erosive osteoarthritis and hypophosphatasia: a family study.

We describe a mother and 2 daughters with familial recurrent calcific periarthritis in a family with an inherited tendency to develop generalized osteoarthritis (OA). Low levels of serum alkaline phosphatase were found in 1 of the daughters while the mother developed erosive OA in later life. HLA typing was noncontributory. However, the 3 individuals with periarthritis possessed blood group A+, while the 6 unaffected family members were O+. The experience of this family adds weight to the case that recurrent calcific periarthritis may be due to an inherited abnormality of alkaline phosphatase production and suggest that this may also be responsible for the recently observed association of calcific periarthritis and erosive OA.